The nation's highest court on Monday said it would let a limited version of Trump's ban on travel from six mostly Muslim countries take effect.

Even the Supreme Court justices seemed surprised by the lack of urgency on the part of the Trump administration.

The decision, immediately seen as Trump's partial victory, blocks the actions of lower federal courts that had put the president'sexecutive order barring US entry from six majority-Muslim countries in the Middle East and Africa completely on hold.

"I think the practical effect is that all the people who are wanting to come into the country actually do have some sort of US connection".

"People, the lawyers and the courts can call it whatever they want, but I am calling it what we need and what it is, a TRAVEL BAN!" he wrote.

Trump says in a statement that his "number one responsibility" is to keep the American people safe. "Today's ruling allows me to use an important tool for protecting our Nation's homeland", Trump said in a written statement. "I am also particularly gratified that the Supreme Court's decision was 9-0", he continued.

But the civil rights organization worries there could be confusion about who is allowed into the USA moving forward.

It was on January 27 - 151 days ago as of Tuesday - that Trump signed an executive order, later struck down by the courts, that banned citizens from Iraq, Syria, Iran, Libya, Somalia, Sudan and Yemen for 90 days and refugees from Syria indefinitely.

There were no noted dissents among the nine justices in the unsigned decision, although three of the conservative justices said they would have gone a step further by granting Trump's request to implement the bans fully while the legal battle continues.

Both bans are now due to partly go into effect in 72 hours, based on a memorandum issued by the Trump administration on June 14.

But instead, his administration regrouped and issued a second order in March. That court also put a hold on separate aspects of the policy that would keep all refugees out of the United States for 120 days and cut by more than half, from 110,000 to 50,000, the cap on refugees in the current government spending year that ends September 30.

The Supreme Court also said in the ruling that it would consider whether the case will be moot by the time it hears it; the ban is supposed to be a temporary one while the government reviews its vetting procedures. The courts, for instance, have consistently ruled against both his travel ban efforts.

"We believe it will not help in confronting terrorism and extremism, but rather will increase the feeling among the nationals of these countries that they are all being targeted, especially given that Yemen is an active partner of the United States in the war on terrorism and that there are joint operations against terrorist elements in Yemen", he said. That means people from the six countries and refugees with no such ties would be barred from entry.